The present invention relates to a continuously variable transmission which continuously varies the transmission ratio (transmission ratio being defined as the RPM or speed ratio) between a driving pulley and a driven pulley, and more particularly to a compacted continuously variable transmission used in a motorized vehicle.
It is known that one type of a continuously variable transmission has a V-belt extending between a driving and driven pulley and controls the number of the revolutions of a driven pulley by varying the size of a V-shaped opening(s) in both the driving and driven pulleys. Thus, the position of the belt on the pulley and the effective diameter of the pulley can be varied, and it is possible to continuously vary the RPM ratio between the input shaft and the output shaft in the continuously variable transmission.
It is also known to form a continuously variable transmission means from a predetermined number of metallic hoops, upon which longitudinally shiftable V-shaped block members are mounted, the members are linked together and extend around the total circumference of the hoops. The driving force of the driving pulley is then transmitted to the driven pulley by the movement of the V-shaped block members.
In the above-described transmission, the distance between the driving and driven pulley varies when the effective diameter of the pulleys vary, to obtain wide transmission ratios. The variation in the distance between the driving and driven pulley results in an increase in the size of the continuously variable transmission. Additionally, if the effective diameter of the driven pulley becomes very small, in order to obtain the wide transmission ratios, the radius of the minimum curve on the V-belt must accordingly be very small, which results in a short useful life for the V-belt.